News, Research

Whale sharks are fascinating creatures. The whale shark is one of only three filter-feeding sharks (the other two are the basking and megamouth shark).It is suggested that whale sharks do not reach maturity until they are over 30 years of age and a size of 9 meters. They can live to be over 100 years old. The whale shark is believed to be highly migratory, they cruise at 3,5 to 5,5 kms per hour and every hour filtering thousands of tons of water, containing very small particles of food, very small plankton including small crustacean and other tiny invertebrates. Its jaws are lined with 300 rows of tiny teeth, approximately 2mm in size.

There have been several reports about small and even very small whale sharks. In the Caribbean Sea, near St. Lucia, a recently born pup was seen swimming and feeding near the surface.

A baby whale shark feeding near the Caribbean Island of St. Lucia.

The capture of a female in July 1996 that was pregnant with 300 pups indicates that whale sharks are ovoviviparous. The eggs remain in the body and the females give birth to live young which are 38 to 55 centimetres long. Most probably the pups are not all born at once, but the female retains sperm from one mating and produces her pups over a longer period.

Whale shark pup and eggs, taken from the same mother.

In the Philippines a juvenile whale shark with a length of 175 cm was discovered in 2006. And on 7 March 2009, marine scientists in the Philippines discovered an even smaller whale shark, a neonatal (just born) individual. The young shark, measuring only 46 centimetres, was found with its tail tied to a stake at a beach in Pilar, Philippines, which was released into the wild. Before this event, only 12 neonatal animals had been described in the scientific literature.

Three weeks later, another juvenile whale shark was found, this time around 63 cm long, and again near Donsol. But there could be whale shark birthing ground on other locations, we just do not know much about the mating and reproductive behaviour of the species. The smallest regularly observed whale sharks are about 2,5 meters in length, and probably around one year old. There is no knowledge where they spend their first year.

And only very recently, a very small pup of around 60 cm length was caught in fishing nets along Gujarat coast, India. It was rescued and released later. Experts working on whale shark conservation are studying the phenomenon which indicates the giant fish swims all the way from Australian shores to Gujarat to reproduce.

Rachel Graham, a whale shark expert and a member of the scientific advisory committee of the Wildlife Trust of India, working on whale shark conservation, states: “The sighting or capture of sub-metre whale sharks is very rare. This particular pup looks like it was most likely born this year and this capture off the coast of Gujarat, further suggests that whale sharks are pupping in the area.”